Channel Mixer effect

The
Amplitude and Compression > Channel Mixer effect alters
the balance of stereo or surround channels, letting you change the
apparent position of sounds, correct mismatched levels, or address
phasing issues.

Channel tabs

Select the output channel.

Input channel sliders

Determine the percentage of the current channels to mix into
the output channel. For a stereo file, for example, an L value of
50 and an R value of 50 results in an output channel that contains
equal audio from the current left and right channels.

Invert

Inverts a channel’s phase. (To understand this key audio
concept, see How
sound waves interact.) Inverting all channels causes no perceived
difference in sound. Inverting only one channel, however, can greatly
change the sound.

Dynamics Processing effect

The
Amplitude And Compression > Dynamics Processing effect
can be used as a compressor, limiter, or expander. As a compressor
and limiter, this effect reduces dynamic range, producing consistent
volume levels. As an expander, it increases dynamic range by reducing
the level of low‑level signals. (With extreme expander settings,
you can create a noise gate that totally eliminates
noise below a specific amplitude threshold.)

The Dynamics Processing effect can produce subtle changes that
you notice only after repeated listening. When applying this effect
in the Waveform Editor, use a copy of the original file so you can
return to the original audio if necessary.

Use the Broadcast Limiter preset to simulate
the processed sound of a contemporary radio station.

Dynamics tab

Graph

Depicts input level along the horizontal ruler (x‑axis)
and the new output level along the vertical ruler (y‑axis).
The default graph, with a straight line from the lower left to the
upper right, depicts a signal that has been left untouched; every
input level has the same output level. Adjusting the graph changes
the relationship between input and output levels, altering dynamic
range.

For example, if a desirable sonic element occurs around
‑20 dB, you can boost the input signal at that level, but leave
everything else unchanged. You can also draw an inverse line (from
the upper left to the lower right) that will dramatically boost quiet
sounds and suppress loud ones.

Add point

Adds control point in graph using numerical input and output levels
you specify. This method is more precise than clicking the graph
to add points.

Flips the graph, converting compression into expansion, or
vice versa.

note: You can invert a graph only if it has points
in the two default corners (‑100, ‑100 and 0, 0) and if its output
level increases from left to right (that is, each control point must
be higher than the one to its left).

Settings tab

General

Provides overall settings.

Look-Ahead
Time

Addresses transient spikes that can occur at the onset of extremely
loud signals that extend beyond the compressor’s Attack Time settings.
Extending Look-Ahead Time causes compression to attack before the audio
gets loud, ensuring that amplitude never exceeds a certain level. Conversely,
reducing Look-Ahead Time may be desirable to enhance the impact of
percussive music like drum hits.

Noise Gating

Completely silences signals that are expanded below a 50-to-1 ratio.

Level Detector

Determines the original input amplitude.

Input Gain

Applies gain to the signal before it enters the Level Detector.

Attack Time

Determines how many milliseconds it takes for the input signal
to register a changed amplitude level. For example, if audio suddenly
drops 30 dB, the specified attack time passes before the input registers
an amplitude change. This avoids erroneous amplitude readings due
to temporary changes.

Release Time

Determines how many milliseconds the current amplitude level is
maintained before another amplitude change can register.

Tip: Use fast attack and release settings for audio
with fast transients, and slower settings for less percussive audio.

Peak mode

Determines levels based on amplitude peaks. This mode is
a bit more difficult to use than RMS, because peaks aren’t precisely
reflected in the Dynamics graph. However, it can be helpful when
audio has loud transient peaks you want to subdue.

RMS mode

Determines levels based on the root-mean-square formula,
an averaging method that more closely matches the way people perceive
volume. This mode precisely reflects amplitudes in the Dynamics
graph. For example, a limiter (flat horizontal line) at ‑10 dB reflects
an average RMS amplitude of ‑10 dB.

Gain Processor

Amplifies or attenuates the signal depending on the amplitude detected.

Output Gain

Applies gain to the output signal after all dynamics processing.

Attack Time

Determines how many milliseconds it takes for the output
signal to reach the specified level. For example, if audio suddenly
drops 30 dB, the specified attack time passes before the output
level changes.

Release Time

Determines how many milliseconds the current output level
is maintained.

note: If the sum of Attack and Release times is
too short (less than about 30 milliseconds), audible artifacts can
be heard. To see good attack and release times for different types
of audio content, choose various options from the Presets menu.

Link Channels

Processes all channels equally, preserving the stereo or surround
balance. For example, a compressed drum beat on the left channel
will reduce the right channel level by an equal amount.

Fade Envelope effect

In the Waveform Editor panel, click the yellow envelope line to add keyframes, and drag them up or down to change amplitude. To quickly select, reposition, or delete multiple keyframes, see Adjust automation with keyframes.

Select the Spline Curves option to create smoother, curved transitions between keyframes, rather than linear transitions. See About spline curves for graphs.

Gain Envelope effect

In the Waveform Editor panel, click the yellow envelope line to add keyframes, and drag them up or down to change amplitude. To quickly select, reposition, or delete multiple keyframes, see Adjust automation with keyframes.

Select the Spline Curves option to create smoother, curved transitions between keyframes, rather than linear transitions. See About spline curves for graphs.

Tip: To
avoid clipping when working with 16‑bit audio, set this value to
no more than ‑0.3 dB. If you set it even lower, to ‑3 dB, you’ll
have a little more clearance for any future edits.

Input Boost

Preamplifies audio before you limit it, making a selection
louder without clipping it. As you increase this level, compression
increases. Try extreme settings to achieve the loud, high‑impact
audio heard in contemporary pop music.

Look-Ahead Time

Sets the amount of time (in milliseconds) generally needed to
attenuate the audio before the loudest peak is hit.

note: Make
sure that the value is at least 5 milliseconds. If this value is
too small, audible distortion effects may occur.

Release Time

Sets the time (in milliseconds) needed for the attenuation
to rebound back 12 dB (or roughly the time needed for audio to resume
normal volume if an extremely loud peak is encountered). In general,
a setting of around 100 (the default) works well and preserves very
low bass frequencies.

note: If this value is too large, audio
may remain very quiet and not resume normal levels for a while.

Link Channels

Links the loudness of all channels together, preserving the stereo
or surround balance.

Multiband Compressor effect

The
Amplitude And Compression > Multiband Compressor effect
lets you independently compress four different frequency bands.
Because each band typically contains unique dynamic content, multiband
compression is a particularly powerful tool for audio mastering.

Controls in the Multiband Compressor let you precisely define
crossover frequencies and apply band‑specific compression settings.
Click Solo buttons to preview bands in isolation, or Bypass buttons
to pass bands through without processing. After you fine‑tune individual
bands, select Link Band Controls to adjust them globally, and then
optimize overall volume with the Output Gain slider and Limiter
settings.

Measure amplitude reduction with red meters that extend from
top (minimal reduction) to bottom (maximum reduction).

Gain

Boosts or cuts amplitude after compression. Possible values
range from ‑18 to +18 dB, where 0 is unity gain.

Ratio

Sets a compression ratio between 1‑to‑1 and 30‑to‑1. For
example, a setting of 3.0 outputs 1 dB for every 3 dB increase above
the compression threshold. Typical settings range from 2.0 to 5.0;
higher settings produce the extremely compressed sound often heard
in pop music.

Attack

Determines how quickly compression is applied when audio
exceeds the threshold. Possible values range from 0 to 500 milliseconds.
The default, 10 milliseconds, works well for a wide range of audio.
Faster settings may work better for audio with fast transients,
but such settings sound unnatural for less percussive audio.

Release

Determines how quickly compression stops after audio drops
below the threshold. Possible values range from 0 to 5000 milliseconds.
The default, 100 milliseconds, works well for a wide range of audio.
Try faster settings for audio with fast transients, and slower settings
for less percussive audio.

Output Gain

Boosts or cuts overall output level after compression. Possible values
range from ‑18 to +18 dB, where 0 is unity gain. Double‑click the
meters to reset peak and clip indicators.

Limiter

Applies limiting after Output Gain, at the end of the signal
path, optimizing overall levels. Specify Threshold, Attack, and
Release settings that are less agressive than similar band‑specific
settings. Then specify a Margin setting to determine the absolute
ceiling relative to 0 dBFS.

Tip: To create extremely
compressed audio, enable the Limiter, and then experiment with very
high Output Gain settings.

Spectrum On Input

Displays the frequency spectrum of the input signal, rather than
the output signal, in the multiband graph. To quickly see the amount
of compression applied to each band, toggle this option on and off.

Brickwall Limiter

Applies immediate, hard limiting at the current Margin setting.
(Deselect this option to apply slower soft limiting, which sounds
less compressed but may exceed the Margin setting.)

note: The
maximum Attack time for brickwall limiting is 5 ms.

Link Band Controls

Lets you globally adjust the compression settings for all bands,
while retaining relative differences between bands.

Tip: To temporarily link band controls, hold down Alt+Shift
(Windows) or Option+Shift (Mac OS). To reset a control in all bands,
hold down Ctrl+Alt+Shift (Windows) or Command+Option+Shift (Mac
OS), and click the control.

Normalize effect (Waveform Editor
only)

Note:

This effect requires offline processing. While it
is open, you cannot edit the waveform, adjust selections, or move
the current-time indicator.

The Amplitude
And Compression > Normalize effect lets you set a peak
level for a file or selection. When you normalize audio to 100%,
you achieve the maximum amplitude that digital audio allows—0 dBFS.
If you’re sending audio to a mastering engineer, however, normalize
audio to between –3 and –6 dBFS, providing a cushion for further
processing.

The Normalize effect amplifies the entire file or selection equally.
For example, if the original audio reaches a loud peak of 80% and
a quiet low of 20%, normalizing to 100% amplifies the loud peak
to 100% and the quiet low to 40%.

Sets the percentage of the highest peak relative to the maximum possible
amplitude.

Tip: Select dB to enter the Normalize
value in decibels instead of a percentage.

Normalize All Channels Equally

Uses all channels of a stereo or surround waveform to calculate
the amplification amount. If this option is deselected, the amount
is calculated separately for each channel, potentially amplifying
one considerably more than others.

DC Bias Adjust

Lets
you adjust the position of the waveform in the wave display. Some
recording hardware may introduce a DC bias, causing the recorded waveform
to appear to be above or below the normal center line in the wave display.
To center the waveform, set the percentage to zero. To skew the
entire selected waveform above or below the center line, specify
a positive or negative percentage.

For examples of highly-compressed audio, listen
to recordings of modern pop music. By contrast, most jazz recordings
are lightly compressed, while typical classical recordings feature
no compression at all.

Threshold

Sets the input level at which compression begins. The best
setting depends on audio content and style. To compress only extreme
peaks and retain more dynamic range, try thresholds around 5 dB
below the peak input level. To highly compress audio and greatly
reduce dynamic range, try settings around 15 dB below the peak input
level.

Ratio

Sets a compression ratio between 1‑to‑1 and 30‑to‑1. For
example, a setting of 3 outputs 1 dB for
every 3-dB increase above the threshold. Typical settings range
from 2 to 5; higher settings produce the extremely compressed sound
often heard in pop music.

Attack

Determines how quickly compression starts after audio exceeds
the Threshold setting. The default, 10 milliseconds, works well
for a wide range of source material. Use faster settings only for
audio with quick transients, such as percussion recordings.

Release

Determines how quickly compression stops when audio drops
below the Threshold setting. The default, 100 milliseconds, works
well for a wide range of audio. Try faster settings for audio with
fast transients, and slower settings for less percussive audio.

Output Gain

Boosts or cuts amplitude after compression. Possible values
range from ‑30 dB to +30 dB, where 0 is unity gain.

To the left of the slider, these meters measure input amplitude.
Double‑click the meters to reset peak and clip indicators.

Gain Reduction meters

To the right of the slider, these meters measure amplitude
reduction with red bars that extend from top (minimal reduction)
to bottom (maximum reduction).

Gain

Boosts or cuts amplitude after compression. Possible values
range from ‑18 to +18 dB, where 0 is unity gain.

Ratio

Sets a compression ratio between 1‑to‑1 and 30‑to‑1. For
example, a setting of 3.0 outputs 1 dB for every 3 dB increase above
the compression threshold. Typical settings range from 2.0 to 5.0;
higher settings produce the extremely compressed sound often heard
in pop music.

Attack

Determines how quickly compression is applied when audio
exceeds the threshold. Possible values range from 0 to 500 milliseconds.
The default, 10 milliseconds, works well for a wide range of audio.
Faster settings may work better for audio with fast transients,
but such settings sound unnatural for less percussive audio.

Release

Determines how quickly compression stops after audio drops
below the threshold. Possible values range from 0 to 5000 milliseconds.
The default, 100 milliseconds, works well for a wide range of audio.
Try faster settings for audio with fast transients, and slower settings
for less percussive audio.

Volume Envelope effect

The Amplitude And Compression > Volume Envelope effect lets you change volume over time with boosts and fades. In the Waveform Editor panel, simply drag the yellow line. The top of the panel represents 100% (normal) amplification; the bottom represents 100% attenuation (silence).

Though the Volume Envelope effect isn’t available in the Multitrack Editor, you can use automation lanes to accomplish the same task. (See Automating track settings.)

Dragging an anchor point in the Editor panel

Yellow envelope line in Editor panel

Drag to adjust amplitude percentage, and click to add keyframes for additional boosts and fades. To quickly select, reposition, or delete multiple keyframes, see Adjust automation with keyframes.